As a key technology in modern wireless communication, a hybrid automatic repeat request (HARQ) technology effectively ensures reliable transmission of wireless data and is widely used in high speed downlink packet access (HSDPA) and long term evolution (LTE). The HARQ can be classified into three types based on an implementation mechanism. The first type of the HARQ (herein “HARQ TypeI”) is also called a conventional ARQ. According to HARQ TypeI, a receive end first performs an error correction for a data packet; if any error fails to be corrected, a data packet repeat request is sent, and the incorrect data packet is discarded; and during retransmission, a same forward error correction code is used, and redundancy information is unchanged. The second type of the HARQ (herein “HARQ TypeII”) belongs to an incremental redundancy (IR) ARQ mechanism of a full redundancy manner. According to HARQ TypeII, during retransmission, system bit information is not included, only new redundancy information is carried to assist in decoding, and the new redundancy information is combined with previously received information at the receive end so as to form a forward error correction code that has a more powerful error correction capability and further reduce an error rate. The third type of the HARQ (herein “HARQ TypeIII”) is also called a partial redundancy HARQ and also belongs to an incremental redundancy mechanism. According to HARQ TypeIII, the receive end combines data experiencing transmission for many times and then decodes the data, and retransmission data includes redundancy and system bits, and can be decoded independently. The LTE/HSDPA uses both the HARQ TypeII and the HARQ TypeIII. The LTE includes four redundant versions (RV), that is RV0-RV3. The HSDPA includes eight redundant versions, that is, RV0-RV8. FIG. 1 is a schematic diagram of a typical HARQ transmission mechanism in the prior art. As shown in FIG. 1, in the typical HARQ transmission mechanism, a transmit end first transmits one RV of one transport block (TB); a receive end receives the RV and then decodes the RV. If the decoding is successful, a positive acknowledgement (ACK) is fed back; and if the decoding fails, a negative acknowledgement (NACK) is fed back. After receiving the NACK, the transmit end continues to send an RV of the TB until the receive end succeeds in decoding the RV and feeds back an ACK.
In the prior art, adaptive modulation and coding (AMC) is used more and more widely in the LTE/HSDPA. Accordingly, a channel quality indicator (CQI) feedback is also mandatory. The receive end first measures a signal to interference plus noise ratio (SINR) and then matches the SINR with the CQI, and the receive end feeds back the matched CQI to the transmit end. A CQI feedback may provide a base station with a basis of dynamically adjusting a modulation and coding manner. The larger a CQI feedback value is, the larger the SINR of the receive end is, the higher a modulation order borne by a radio link is, and the higher a channel coding rate is. Each CQI corresponds to a curve of mappings between the SINRs and block error rates (BLER). FIG. 2 is a schematic diagram of a curve of mappings between SINRs and BLERs in the prior art. For the receive end, a CQI fed back is the highest CQI that can be supported in a channel condition when a requirement that BLER<=0.1 in transmission over an air interface for one time is met, so that a possible highest instantaneous throughput is supported.
However, when the receive end seeks high throughput, required power consumption is relatively high. This reduces the data transmission efficiency.